The present invention is an improvement to rotary bit lubrication systems such as disclosed in the prior art U.S. Pat. No. 3,841,422 to Crow. Of the known prior art, the Crow patent is the nearest to the present invention.
The Crow patent discloses a bit body defining a lubricant reservoir, a bearing lubricating area, a first lubricant passageway including a mechanical check valve for providing one-way flow of lubricant from the reservoir to the bearing area, and a second lubricant passageway including a mechanical check valve for providing one-way flow of lubricant from the bearing area back to the reservoir. The two check valves, with the cone cutter as a pump, serve as pump valves to circulate lubricant through the bearing space.